Lid with a pressure release hole and a removable seal, for vacuum sealing of glasses and other glass containers used to pack foodstuff

ABSTRACT

A lid for sealing a container. The lid adheres to the container by a vacuum formed within the container. The lid is formed of a substantially circular panel having a flanged perimeter and a concave depression on an upper side of the circular panel. A pressure release hole extends through the concave depression of the circular panel and sanitary coating is disposed on a lower side of the circular panel. A first adhesive material is applied to the lower side of the lid by fusion to the sanitary coating to form a thin film over the release hole, and a second adhesive material is disposed in the concave depression on the upper side of the lid to form a removable seal. The second adhesive material has the same properties as the first adhesive material.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of co-pendingapplication U.S. Ser. No. 07/888,175, filed May 26, 1992, now U.S. Pat.No. 5,275,679, entitled "PROCESS TO FORM A PRESSURE RELEASE HOLE WITHREMOVABLE SEAL, FOR EASY OPENING ON METAL LIDS WITH VACUUM SEALING OFGLASSES AND OTHER GLASS CONTAINERS USED TO PACK FOODSTUFF".

FIELD OF THE INVENTION

This invention is related to and is the object of a process to form apressure release hole, with removable seal, for easy opening, on metallids for vacuum sealing of glasses and other glass containers used topack foodstuff.

The metal lid, provided with a hole and removable seal, obtained withthis production process, has a purpose to provide a lid which may beeasily opened, without the use of any special tool or instrument, withsuch lids being used for vacuum sealing of glasses and other glasscontainers used to pack foodstuff, particularly those in which theproduct is filled at high temperature, with the sealing of such packingsbeing achieved by steam jets, from which, after the cooling of theproduct and the condensation of the steam contained within thecontainers, vacuum is formed, resulting in the air tight sealing of suchpacking devices.

BACKGROUND OF THE INVENTION

This metal lid, for which a new process to make the pressure releasehole was created, with a removable seal, the removal of which allows theeasy opening of the container, by the elimination of the internal vacuumof the container, is formed by a metal lid of the common, known type,usually made of aluminum or iron sheet plate, constituted by a circularpanel with a downward turned rim, having, along its inner peripherialcircumference, a circular groove containing a sealing gasket, made of aresin-like material, such as "plastisol" or other similar material, usedto create a type of seat on the rim of the glass or of the other glasscontainer, with said metal lid not being part of this invention.

This type of metal lid has been used, normally, to seal glass containersto pack different foodstuff, and the sealing being achieved by beadingand by the use of special clamps, with such a system requiring the useof thick-walled glass containers, and, also, such containers having abeading in its rim, in order to co-operate with the downward rim of thelid, during the beading process, a process that, besides beinguneconomic, due to the use of larger quantities of material for thecontainers, harms its visual aspects, due to the heavy appearance, whichis not proper for the later use of the container as a common waterglass, a use which is a sale promotion for the product.

With the improvement and evolution of such type of packings, namely,those containers formed by glass tumblers, their sealing has beennormally achieved by vacuum, in other words, the vacuum formed withinthe packing container is used as a sealing element and lid fixingelement, for its air-tight sealing, therefore excluding the use ofclamps and beading machines, this being a considerable improvement forsuch glass containers, mainly those shaped as tumblers, for they werenot subject to the pressure and impact of beading clamps any more, andwith the containers being made with relatively thin walls, eliminatingthe need of a heavy rim or bead at the open mouth, offering them abetter look and the best possibility of being used as domestic drinkingglasses, with the same conditions of the glass tumblers made fordrinking purposes.

However, even considering the new sealing system of a metal lid as moreeconomic and offering a better look to the packed products, offering theopportunity of a later use of the glass container as a drinking glass,it still requires, for the opening or removal of the lid, the use of apointed instrument, such as a pointed knife, to be introduced under saidrim or skirt of the metal lid, in order to achieve the elimination ofvacuum and the total opening or removal of the lid, and such anoperation not only makes it difficult to open the packings, but maycreate a possible hazard to the operator's hands.

SUMMARY OF THE INVENTION

In order to provide better conditions for an easy opening, without theneed of any other tool or instrument, a metal lid with a hole and aremovable seal was developed, the characteristics of which, formanufacture and use, are the object of this invention, and provide atotal guarantee against any violation of the packing, especially in thesale stations, because the process for the opening of the pressurerelease hole and the placing of the removable seal does not allow thereplacement of the seal after the lid is taken out, showing,immediately, an eventual violation of the product in the sale station,because once the vacuum is eliminated, by the removal of the seal, thelid becomes free and the product is not accepted by the purchaser.

Another advantage of the new process to make the pressure release holeand respective removable seal is that, thanks to the previousapplication, on the inner face of the lid and in the opening which formsthe hole, of a thin film or membrane, of the same resin-like material("plastisol" or similar material), which forms the seal, with such filmclosing said hole, in its lower portion, therefore not allowing theentering or attack of any acid substances from the products against theportion of the lid, in the hole, which remains unprotected by thefinishing varnish, avoiding, also, that the seal forming material, whenapplied in a fused state on the concave area where the hole is made,enters the hole, forming a small bead or residue of such material in thelower face of the lid, which could constitute an obstacle for the easyand total removal of the seal from the breathing hole, therefore harmingthe perfect performance of the hole's function in the elimination ofvacuum from the interior of the packing and easy opening and removal ofthe lid.

BRIEF DESCRIPTION OF THE DRAWINGS

The new process to form a pressure release hole with removable seal, foreasy opening of metal lids for vacuum sealing of glasses and other glasscontainers used to pack foodstuff is represented in the attacheddrawings, where:

FIG. 1--Lateral view and diametral cross-section, showing the metal lidwith the pressure release hole and removable seal, obtained by the newmanufacture process, with the lid applied through vacuum effect on themouth of a packing glass, full with the product;

FIG. 2--The same lateral view in diametral cross-section, showing themetal lid at the moment of the removal of the seal from the pressurerelease hole, therefore eliminating the vacuum in the interior of thepackage;

FIG. 3--The same lateral view in diametral cross-section, showing themetal lid out of the packing glass, providing easy opening of thevolume;

FIG. 4--A top view of the metal lid, with the pressure release hole andremovable seal;

FIG. 5--Cross-section view, showing, enlarged, a central portion of themetal lid panel, where, following the principles of this new process,the pressure release hole is made, by removing a circular portion fromthe material forming the metal lid;

FIG. 6--The same view, in enlarged detail, of the Figure above, showinga subsequent phase of the process, through which the lower portion ofthe hole is closed by a thin film of resin-like material ("plastisol" orsimilar material), of thermo-plastic and melting characteristics;

FIG. 7--The same view, in enlarged detail, of the Figure above, showing,in a subsequent operation of the process in question, the application ofthe resin-like material ("plastisol" or similar material) in liquid orfused state, which will form the removable seal, filling of the hole andmerging by melting together, with the thin film applied to the lowerportion of the pressure release hole;

FIG. 8--The same view, in enlarged detail, of the above Figures, showingthe moment of removal of the seal from the hole, breaking up the endportion of the sealing material contained within the hole and which wasconnected to the thin film applied to the lower portion of the hole,therefore providing total and full opening of the pressure release hole,in order to eliminate vacuum from the interior of the packing;

FIG. 9--Cut-out view, enlarged and in detail, of a portion of the metallid, showing, for comparison purposes, an already known and inconvenientprocess to form the pressure release hole with seal, through which therunning-out of the resin-like material, when in liquid state, occurstowards the lower portion of the hole, not protected by the thin film ofresin-like material, therefore forming, after its solidification, a beador portion of residues on said portion, making difficult or impossiblethe total removal of the seal from the pressure release hole;

FIG. 10--The same view of the Figure above, showing the harmful effectsderived from the formation of the bead or residues in the lower portionof the hole, upon the removal of the seal;

FIG. 11--Lateral view, with partial cut, of a glass-packing tumbler,closed by a metal lid under vacuum, with the vacuum or pressure releasehole and seal, obtained through the new process, for easy removal of thelid, a process which allows the use of thin-wall glass tumblers, withoutthe need of beadings or heavy rims, thanks to the elimination of theneed to use beading or flanging clamps;

FIG. 12--Lateral view, with partial cut-out portion, showing, forcomparison and elucidation purposes, a closed glass tumbler packingunit, the metal lid of which is closed by the beading or flangingoperation with the use of a special clamp, requiring the use of glasscontainers with heavy rims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Describing, with more details, this invention, and following theattached drawings, the metal lid used for vacuum sealing of glasstumblers or other glass containers, having a pressure or vacuum releasehole with a removable seal, for easy opening, it is noticed that suchmetal lid, normally formed by a circular panel (1) made out of aluminiumor iron sheet plate, with a downward flange or rim (2), with a groove,in its internal periphery, to contain a sealing gasket (3) made out ofresin-like material, such as "plastisol" or similar compound.

Such metal lid, normally used for vacuum sealing of glass tumblers usedfor the packing of foodstuff, has, at a preferably central portion ofits panel (1), a concave circular depression (4) destined to receive adrop of the resin-like material, in liquid and melted state, such as"plastisol" or a similar compound, to form a removable seal (5), whichwill act as a seal for the pressure of vacuum release hole (6) made onthe bottom and central portion of said concave portion (4).

According to the process for the making of said pressure or vacuumrelease hole (6) in the panel of the metal lid (1), which is normallylined in its lower face by a thin film of sanitary varnish (7), and inthe center portion of said concave depression (4), a hole (6) is made,by removing a disk portion (8) out of the lid-forming metal panel (1),by a punching process, as shown, in detail, in FIG. 5 of the drawings,with the inner and cut edges (9) of said hole remaining unprotected bysaid sanitary and protective varnish film (7).

In a subsequent operation of the process, shown in detail in FIG. 6, inthe lower portion of the hole (6) and in its cut edge, a thin film (10)of the resin-like material ("plastisol" or similar compound) is applied,having the same thermo-plastic characteristics of the resin-likematerial which forms the seal (5), and such film, due to itsthermo-plastic characteristics, fuses itself to the varnish film (7)lining the lower face of the lid panel (1), therefore forming a seal insaid lower portion of the hole (6) and, at the same time, it eliminatesthe possibility of a contact with the cutting edges (9) of the hole withthe internal or lower portion of the metal lid panel (1), thereforeeliminating the possibility of contact with acid substances of theproducts in said portion (9) of the hole, which is not protected by thesanitary varnish.

After the application of said film (10) which seals the hole (6) in itslower portion and in its cutting edge, in a subsequent operation shownin detail in FIG. 7 of the drawings, a drop of the resin-like material"plastisol" or similar compound having the same characteristics of thematerial forming the thin film (10) is applied to the concave circulardepression area (4), penetrating into the hole (6), and fusing, throughthe stem portion (11), to the thin film (10), as shown in detail in FIG.7 of the drawings. Such a process avoids and blocks the running orpouring out of the resin-like material forming the seal (5), whenapplied in liquid and fused state to the concave depression (4), towardsthe lower portion of the hole (6), with the previously applied thin film(10) avoiding such running or pouring out, which could form a bead (12)or a residual drop of the resin-like material through the lower portionof the hole, as shown, for elucidative purposes, in FIG. 9, a fact whichcould harm the easy and total removal of the seal (12a) upon the removalof the lid, as shown in FIG. 10, with the consequent difficulty inliberating the vacuum release hole (12b) and the consequent eliminationof vacuum formed within the packing container, and making difficult theremoval of the lid.

As it is noticed, from this process of making the vacuum release holeand respective removable seal, besides avoiding the running or pouringout of the resin-like material ("plastisol" or similar compound) whichforms the seal (5) in the hole (6), applied in the liquid or fused statewithin the concave region (4), thanks to the previous application of thethin film (10) to the lower portion of the hole (6), this operationallows that such a thin film (10) will provide, at the same time, atotal protection of the cutting edges or rims (9) of the hole, which arenot protected by the sanitary varnish, therefore avoiding the attack, byacids contained in the packed product, which could cause rust oroxidation of the metal lid, a condition particularly important to lidsmade out of iron sheet, which are economically advantageous whencompared with aluminium lids.

Following this process, upon removing the seal (5), for the first use ofthe product, and as shown by FIGS. 2 and 8 of the drawings, the stemportion (11) located within the vacuum or pressure releasing hole (6),when applied upwards, breaks the film (10), to which it is connected,removing or pulling out a central portion of said film (10), thereforeliberating, totally, the hole (6), and breaking the vacuum formed withinthe empty space (13) normally formed in the upper part of the product(14) within the container, between the product's upper surface and thelower face of the lid (1) causing the easy removal of the metal lid, asshown in FIG. 3.

An additional advantage of this process relative to the production ofthe vacuum or pressure releasing hole and respective seal, for metallids used in vacuum sealing, is the fact that, using the resin-likematerial ("plastisol" or similar compound) to form the removable seal(5), its solidification is achieved by vulcanization, and not only by asimple gluing, avoiding the possibility of, after the first opening ofthe lid and removal of the seal (5), it may be reapplied or replacedunder the same conditions for fixing and adherence, with the purchaseror client noticing, immediately, eventual violation of the packing, inthe sale station, for after the removal of such seal, the lid willremain free, due to elimination of vacuum, the only element whichretains the metal lid in place, and the purchaser will not accept thepackaging in such a condition.

It should be noticed, further, that the making of the vacuum or pressurerelease hole and the respective seal under the new process, hasadditional advantages, such as the fact that the metal lid, normallylined with a sanitary varnish (7) in its lower face, which contacts thefood product, will not have an interruption in its protective layer orfilm, thanks to the melting characteristics of the sanitary varnish (7)and of the resin-like material ("plastisol") which forms the seal (5)and the thin film (10), made of the same material, of controlledadherence, providing the lid with a perfect and total protection againstoxidation, a fact that represents a guaranty of integrity to the lid andto the food products packed in such type of packing material.

Another advantage to be taken into consideration, in this system ofvacuum sealing of glass tumblers by metal lids having a vacuum orpressure release hole and a removable seal, manufactured as per this newprocess, is that this type of packing becomes easy to be opened, bysimple removal of the seal (5) from the vacuum or pressure release hole(6), without the need to use any special instrument or tool, or withoutthe use of any efforts by the person who is opening the unit, andoffering, as an additional advantage, the fact that the glass tumblersmay be made with relatively thinner walls, without the undesirable heavyrim along their mouths, therefore providing, for the glasses, economy inmaterial, and a more pleasant and appropriate look, for their later useas domestic drinking glasses, as shown, elucidatively and comparatively,in FIG. 11, with real advantages when compared with other glasscontainers sealed with metal lids with beading and flanging operation,which require heavier glass walls, to resist the impact of the beadingclamps, and the formation of heavy beads (15) along the edges of theglass containers, for the beading of the metal lids, as shown in FIG. 12of the drawings.

As noticed, this new process for the manufacture of a vacuum or pressurereleasing hole and respective removable seal, the object of thisinvention, provides the metal lids so produced with the followingadvantages:

a) offers complete and perfect protection to the metal plate of the lid,against acid substances contained in foodstuff, mainly preserves andfood products preserved in brine, avoiding oxidation and contaminationof the products, and assuring the integrity and durability of the metallid, thanks to the total protection provided by the film (10) applied tothe lower portion of the vacuum and pressure release hole (6),protecting the cut edges or rims (9) of such a hole (6).

b) avoids the running or pouring out of the resin-like material("plastisol"), which forms the removable seal (5), when it is applied,in the liquid state, to the concave circular depression (4), andavoiding the passage of such material towards the lower portion of thehole (6) and the undesirable formation of a bead (12), which hinders theeasy removal of the seal and of the lid, by the liberation and clearingof the vacuum and pressure release hole (6) upon the removal of saidseal (5).

c) thanks to the breaking of the thin film (10), connected by fusion tothe lower portion of the stem portion (11), a total and guaranteedopening of the vacuum release hole (6), with the efficient eliminationof vacuum, for easy removal of the metal lid, is offered by this system,due to the mechanical weakness of said thin film (10).

I claim:
 1. A lid for sealing a container, the lid adhering to thecontainer by a vacuum formed within the container, the lid comprising:asubstantially circular panel having a flanged perimeter and a concavedepression on an upper side of the circular panel; a sanitary coatingdisposed on a lower side of the circular panel; a pressure release holeextending through the concave depression of the circular panel; a firstadhesive material applied to a lower side of the circular panel byfusion to the sanitary coating to form a thin film over the releasehole; and a second adhesive material disposed in the concave depressionon the upper side of the circular panel to form a removable seal, thesecond adhesive material having the same properties as the firstadhesive material.
 2. The lid of claim 1 wherein the first and secondadhesive materials are a vulcanized resin applied in a liquid state thatsolidifies to the circular panel and the first and second adhesivematerials melt together to form a unitary seal.
 3. A releasable lid fora vacuum sealed container, the lid being released from the containerupon discharge of the vacuum, the lid comprising:a panel; a vacuumdischarge hole extending through the panel; and a removable adhesivematerial disposed on the panel and sealing the vacuum discharge hole,whereby removal of the adhesive material from the panel discharges thevacuum and releases the lid from the container.
 4. The lid of claim 3wherein the lid further comprises a substantially circular panel havinga flanged perimeter.
 5. The lid of claim 3 further comprising asubstantially circular panel having a concave depression on an upperside of the circular panel.
 6. The lid of claim 3 wherein the removableadhesive material comprises a first adhesive material disposed on alower side of the panel and a second adhesive material disposed on anupper side of the panel.
 7. The lid of claim 6 wherein the firstadhesive material and the second adhesive material form a bond throughthe vacuum discharge hole.
 8. The lid of claim 7 wherein the firstadhesive material and the second adhesive material are substantially thesame.
 9. The lid of claim 8 further comprising a sanitary coatingdisposed on the lower side of the panel.
 10. The lid of claim 8 whereinthe panel is a substantially circular panel having a flanged perimeter.11. The lid of claim 10 wherein the panel further comprises a concavedepression on the upper side of the panel wherein the vacuum dischargehole is disposed in the concave depression.
 12. The lid of claim 8wherein the first adhesive material and the second adhesive materialcomprise a vulcanized resin that is applied to the panel in a liquidstate and later solidifies to the panel so that the first adhesivematerial and the second adhesive material bond together through thevacuum discharge hole to form a unitary seal.